GM OBD1 Systems
CODE RETRIEVAL PROCEDURE
OBD1 91
Retrieving and using Diagnostic Trouble Codes (DTCs) for
troubleshooting vehicle operation is only one part of an
overall diagnostic strategy.
Intermittent/History DTCs
Intermittent/History DTCs are stored in the computer's memory for
problems that occur intermittently, or for problems that happened in
the past but are not currently present. Intermittent DTCs may cause
the Malfunction Indicator light to flicker or stay on until the
intermittent malfunction goes away. However, the corresponding
fault code will be stored in memory as a history DTC. If the
malfunction that caused the history DTC to set does not recur within
a predetermined length of time (usually within 40-80 ignition key
start cycles), the computer will automatically erase the related fault
code from its memory.
CODE RETRIEVAL PROCEDURE
Never replace a part based only on the DTC definition.
Each DTC has a set of testing procedures, instructions
and flow charts that must be followed to confirm the
location of the problem. This information is found in the
vehicle's service manual. Always refer to the vehicle's
service manual for detailed testing instructions.
Check your vehicle thoroughly before performing
any test. See BEFORE YOU BEGIN on page 31
for details.
ALWAYS observe safety precautions whenever working on a
vehicle. See Safety Precautions on page 3 for more
information.
1.
Locate the vehicle's Data Link Connector (DLC). See DATA LINK
CONNECTOR (DLC) on page 90 for connector location.
Some DLCs have a plastic cover that must be removed before
connecting the Scan Tool's cable connector.
2.
Connect the Scan Tool cable (with the GM
Connector Cable Adaptor attached) to the
Scan Tool, then connect the adaptor to the
vehicle’s DLC. Press the POWER/LINK
button to turn the Scan Tool ON,
then press the ENTER
button to
continue.
The GM OBD1 menu displays.
3.
To view codes in the Scan Tool’s memory:
Use the UP
and DOWN
buttons, as necessary, to highlight
Review DTCs, then press the ENTER
button.
Summary of Contents for 31403
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